Several blood thinners are available to prevent stroke in people with atrial fibrillation (AFib). The safest blood thinner to use depends on various factors, such as medical conditions and overall health.

One of the main focuses of AFib treatment is to reduce the likelihood of stroke by preventing the formation of blood clots. Blood thinners can decrease the rate of AFib-related stroke by more than 50%.

Until the last decade, warfarin was the only drug approved by the Food and Drug Administration (FDA). Newer blood thinners are now available to prevent stroke in people with AFib.

This article explores blood thinners doctors may prescribe for AFib and their possible side effects. It also explores other potential treatments doctors may use to treat AFib.

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Blood thinners are medications that healthcare professionals may refer to as anticoagulants. These medications stop blood clots from forming and getting bigger but do not break up existing clots.

Certain blood thinners may be safer for a person than others, depending on their medical conditions and medications. In addition, blood thinners may not be suitable for some people with AFib.

Vitamin K antagonists

Doctors commonly prescribe vitamin K antagonists, such as warfarin, for people with AFib. These medications block vitamin K, which the body uses to help form blood clots.

However, warfarin has a narrow therapeutic window of dosing. This means there is a small difference between an effective dose and a dose that causes toxic adverse effects. Certain factors can also alter warfarin’s effect on the body:

New oral anticoagulants (NOACs)

NOACs have two main categories:

  • Direct thrombin inhibitors: These medications block the action of thrombin, an essential component in blood clot formation. Examples include dabigatran, bivalirudin, and argatroban.
  • Factor Xa inhibitors: These bind directly to factor Xa, the protein responsible for creating thrombin, inhibiting it from making thrombin. Examples of these medications are rivaroxaban, edoxaban, betrixaban, and apixaban.

People may also refer to NOACs as direct oral anticoagulants (DOACs) and target-specific oral anticoagulants (TSOACs).

The 2019 guidelines by the American College of Cardiology (ACC) and the American Heart Association (AHA) recommend NOACs over warfarin, although NOACs are not suitable for everyone.

Some research indicates that newer anticoagulants may not be suitable for people with mechanical heart valves and people with moderate to severe mitral valve stenosis. The ACC instead recommends warfarin for people with mechanical heart valves.

The FDA also notes that dabigatran, rivaroxaban, and apixaban are less likely to cause hemorrhagic stroke than warfarin. They also have other benefits:

  • fewer drug interactions
  • rapid onset, eliminating the need to bridge with another medication that is necessary with warfarin
  • potential freedom from periodic blood test monitoring
  • clears from the body quicker than warfarin

However, a person should take NOACs as directed by a doctor to receive the maximum benefit for stroke prevention.

Doctors may not prescribe NOACs to people with kidney issues, or they may lower a person’s dose and recommend frequent kidney function monitoring.

A 2015 study on the effects of dabigatran and rivaroxaban on people on dialysis found that these drugs carry a higher risk of death from loss of blood than warfarin for this group.

These drugs also differ in their gastrointestinal (GI) safety profile, particularly in relation to GI bleeding. In a 2016 study, the authors found apixaban had the most ideal GI safety profile, while rivaroxaban had the least favorable profile.

A person should speak with a healthcare professional to determine which blood thinner may be best for them or if an alternative treatment may be more appropriate.

The drugs discussed in the section above carry a bleeding risk. This risk can be related to the drug itself or the person taking it.

For example, a 2020 review found that the risk of significant bleeding is higher in warfarin than in NOACs. Other medications, such as antiplatelet agents, can also increase a person’s risk of bleeding.

Other person-related factors include:

  • age
  • race
  • underlying medical conditions
  • coagulopathy, which affects how the body manages blood clotting
  • recent surgery

A person taking warfarin requires regular blood tests to ensure they have the correct dose. A dose that is too low does not help reduce a person’s risk of stroke, but too much can lead to internal bleeding.

In cases of significant and life threatening bleeding, all these medications have reversal agents to counteract their effects.

A healthcare professional will consider if the benefits of a blood thinner outweigh its risks before deciding whether to prescribe it on an individual basis.

Aside from blood thinners, doctors typically prescribe heart rhythm-controlling or heart-rate-controlling medications to restore a person’s natural heart rate and rhythm.

They may also give medications or other treatment for underlying conditions that reduce a person’s risk factors for AFib. Some of these medications aim to address the following:

Doctors typically prescribe medications and lifestyle changes that may help prevent further complications associated with Afib. These include:

A healthcare professional may also consider medical procedures and surgery when medications and lifestyle changes fail to address a person’s AFib symptoms. These treatment options may include:

Several blood thinners help prevent strokes and blood clots in people with atrial fibrillation. However, these drugs come with risks and side effects, which doctors discuss with people before starting treatment.

In addition to medications, a healthcare professional may also recommend lifestyle changes and procedures or surgery depending on the severity of a person’s AFib.

A person should speak with a doctor who will consider factors such as age, overall health, and existing health conditions when determining the most suitable treatments for them.